Speedometer.



PATENTED- JUNE 4, 1907.

m m T WE EM TO D .E w T aw am 7 w 5 5 00 m N APPLICATION FILED OUT; 22, i906.

Inventor (70721. 2? Jew c57 5 v 1 UNITED. STATES PATENT OFFICE;- I

JOHN K. STEW-ART, OF CHICAGO, ILLINOIS.

SPEEDOM'ETER.

:a part thereof.

The purpose of this invention is to provide an Improved device by which at a glance the speed of a traveling vehicle may be ascertained.

It consists in the devices for transmitting the movement of a part which is centrifugally actuated, and modifying that movement for actuating an index fin'ger proportionately to the increase of speed, and which'consists also of specific'detalls of construction, as may be understood from the specifications and as set out in the claims.

In the drawings :Figure 1 is a front elevation of a speed indicator involving this invention, the glazed front cap being removed. Fig. 2 is a section at the line 22 on Fig. 1 with the cap in place. Fig. 3 is a section at the line 33 on Fig. 1 with the cap in place. Fig. 4 is a section at the line 4-4 on Fig. 2.

The mechanism of this device is mounted in a case, 1, having a front closed by a glazed cap, 2.

3 is a shaft journaled in the case and protruding therefrom for connection by any means (not shown) with the part which re tates in definite time with the wheels of the vehicle whose speed is to be measured or indicated. Onthis shaft, 3, there is pivotally mounted for rotation with the shaft, but so as to swing about its pivot, a fly-wheel or centrifug'ally actuated element,-4.

5 is a sleeve mounted for sliding on the shaft, 3, and connected by a link, 6, with' the flywheel, 4, so that the rocking of the flywheel about its pivot to the shaft tends to slide the sleeve and vice versa, the sliding of the sleeve on the shaft tends to rock the fly-wheel about its pivot. A spring, 7, coiled about the shaft and'sleeve reacts against a shoulder, 7, on the sleeve and against a pin, 8, set through the shaft to force the sleeve yieldingly away from the pivot of the flywheel, and thereby to hold the fly-wheel inclined away from position at right angles to the shaft toward a position parallel to the shaft, its limit being an oblique position at Specification of Letters Patent.

Application filed'October 22,1906. Serial No. 339,897.

Patented June 4, 1907.

which it is shown in the various figures. The pin, 8, takes through'slots in the. sleeve to prevent the sleeve from rotatin on the shaft and cause it to rotate with the s aft and with the fiy-wheel. The sleeve is provided with, or has mounted for movement as rigid with it, a disk, 9, which has a peripheral flange, 9,

projecting from the side toward the flywheel. i

10 is a bracket'mounted upon the inside of the case, having'pivot hearings in a plane at right angles to the axis of the shaft, 3, for a rock-shaft, 11, which carries an index finger,

1 2, mounted in osition to swing over a graduatedsegment ial, 13. This rock-shaft has. a short lever arm, 14, connected by a link, 15, to a lever arm, 16, of a second rock-shaft, 17 mounted in a bracket, 18, which is also secured upon the inner side of the case at a distance of about 120 degrees around from the bracket, 10. To the lever arm, 16, there is rigidly secured a cam-plate, 19, ofwhich the cam portion consists of two flanges, 19 and 19, which project from the cam plate ina plane diametric with respect to the shaft, 3, and at a position to be encountered by the flange, 9, of the disk, 9, which is formed rigidly, as described, With the sleeve, 5 At themost remote position of the disk from the flywheel,-'the osition at which it appears in full line in al l the figures of the drawings, the flange, 9, bears' upon the edge of the cam flange, 19, near the outer limit of said edge, and as the rotation of the shaft causing the fly-wheel, by centrifugal force, to tend to as sume a position at right angles to. the shaft,

IOC

flanges, 19 and 19 of the cam plate. From this point the pressure of the disk flange, 9, operates against both the cam flanges, 19 and 19 the two cam flanges being shaped in view of their different radii of movement about the rock-shaft, 17, so that they share substantially equally the pressure of the sliding element, 9 and this prevents the tendency to cramp the sleeve, 5, on the shaft, which would result from having the disk flange, -9, encounter all the resistance to its movement at one side 'ofthe axis. The pressure of the '5 flange, 9, against the two cam flanges cont tinues the swinging movement of the lever,-

16, inthe same direction about the axis of its rock-shaftand continues the swinging of the index finger over the dial. A spring, 20, is provided coiled about the pivot spindle, 4

.of the fly-wheel, 4, reacting at one side of the.

' pivot against the shaft, 3, and at the other side against the pivot of the link, 6, to the fly-wheel, tending to hold the fiy-wheel yield- I 5. ingly in the position most nearly parallel to the shaft,that is, the position from which centrifugal force due to the rotation of theshaft'would tend to swing it Either of the springs, or 7, may be chiefly relied upon 2 for resisting the centrifugal action; but preferably the spring, 20, is the stronger or stiffer o the two, the spring, 7, being merely calcu.

which connects the two moving parts ex' tends in different parts of the movement. A spring, 21, connected at one end to the ease and at the other end to the lever, 16, resists the movement of the lever about its pivot 40 the disk, 9, against the cam flanges, 19 and l9 by the approach of the disk toward a pivot of the fly-wheel which is produce'd by the, centrifugal movement of .the fly-wheel toward position at right angles to .the shaft upon increase of speed. All the springs, 7, 20 and .21, it will be seen, therefore, operate to the contrary of the centrifugal tendency, and eachbeing adapted to resist the move- 5 ment of the part withwhich it is associated,

by the most direct possible opposition to such movement there is eliminated from the frictional resistance of the parts all resistance due to cramping from indirect action.

It will be understood that in order to cause the angular movement of the index finger to correspond. perfectly to the increase of speed, in view of the following variations,- (a) variation of the centrifugal force of the flyproaches position at right angles to the sha t, such increase being not, however, in direct arithmetical ratio to the change ofspeed; (b) variation oftension of the spring, 20,

5 which increases substantially in direct ratio caused -by the presence of'the flange, 9 of' wheel which steadily increases as it a to the angular change of position of the flywheel about its pivot; (c) variation of ten, sion ofthe spring, 7, which increases in direct ratio to the sliding movement of the sleeve,5; (d) variation in. the tension of the spring, 21, which increases as the lever,

16, swings about its pivot under the pressure of the flange, 9 of the disk, 9, but not in direct ratio either to the angular movement of the lever or sliding movement of the sleeve, 7 5 i a net compensation must be provided to. absorb, so to speak, all these variations and establish a uniform direct ratio between the increase of speed of the shaft, and the movement of the index finger over the dial, due to 0 said increase of speed. This net compensation is provided in the contour of the cam flanges, 19 and 19*, which together may be considered as a single cam, although they are separated by approximately the amount of the diameter of the disk,9. The contour of this cam will be necessarily worked out with each individual instrument, absolute uniformity in all thei'nstruments' of the same general makebeing'impossible because of the impossibility of making direct springs of absolutely the same stiffness so as to yield exactly the same amount for a given amount of pull exerted by the centrifugal tendency of In practice the springs can be 5 sufficiently nearly uniform so that the cam flanges can be originally made to conform to a general contour approximating that which will yie-id accurately the desired result, and this general contour can be rendered suifi--1oc ciently exact for each instrument by the ad' juster or calibrator in fitting up each instrument upon a final test.

I claim i I 1'. In a speedometer, a shaft adapted to be driven by the .mechanism whose speed is to be measured; a centrifugally-operated ele* ment on the shaft revolving therewith; a sliding element on the shaft connected with said centrifugally-operated element; an inno dex finger and a graduated scale over which it moves; a pivotally, mounted cam carrier operatively connected with the index finger, and a cam thereon whose cam edge or surface is acted upon by pressure thereagainst of said sliding element for converting the sliding movement, with modification, into the swinging movement of the index finger.

- 2. In a speedometer, a shaft adapted to be driven by the mechanism whose speed is to be measured a centrifugally=operated ele-v ment carried by the shaft; an element mounted on the shaft for sliding thereon and rotation therewith connected with the centrifugally-operated element; a pivoted indi cater and a graeuatedscale over which it moves; a pivotally mounted cam carrier operatively connectedwith the indicator, and-a. cam thereon whcse cam edge or surface is actedupon by p1 essur'e thereagainst of the" 1 0 sliding element for converting the sliding movement thereof, with modification, into the swinging movement of the indicator.

3. In a speedometer, a shaft adapted to be driven by the mechanism whose speed is to be measured; a centrifugally-operated ele ment pivoted on the shaft and revolving therewith; an element mounted on the shaft for movement longitudinally thereof; means by which the pivoted element communicates such longitudinal movement; an indicator and a graduated scale over which it moves; a pivoted cam carrier operatively connected with the indicator, and a cam thereon whose cam edge is acted upon by pressure thereagainst of said longitudinally moving element for converting said longitudinal movement,with modification, into the movement of the indicator over the scale.

4. In a speedometer, a shaft adapted to be driven by the mechanism whose speed is to be measured; a centrifugally-operatedelement carried by the shaft a spring which resists such centrifugal action; an element mounted for movement longitudinally with respect to the shaft; means by which such movement is derived from the centrifugal movement of said centrifugally-operated element; an indicator and a graduated scale over which it moves; a pivoted cam carrier operatively connected with the indicator, and a cam thereon whose cam edge or surface is acted upon by pressure thereagainst of the longitudinally moving element for deriving the movement of the index finger from said longitudinal movement, with modification due to the form of the cam.

5. In a speedometer, a shaft adapted to be drivon'by the mechanism whose speed is to be rm-asured a centrifugally-operated element carried by the shaft; a spring which re.- sists such centrifugal movement; an element mounted for movement longitudinallywith the shaft; a spring which resists such longi tudinal movement; connections for deriving such longitudinal movement from the cen trifugal movement of the centrifugally-operated element; an indicator and a graduated scale over which it moves; a pivot-ed cam carrier operatively connected with the indicator,

and a cam thereon whose cam edge or surface is acted uponby pressure thereagainst of the longitudinally moving element for deriving from such longitudinal movement the movement of the indicator over the scale, with modification due to the shape of the cam.

6. In a speedometer, a shaft adapted to be driven by the mechanism whose speed is to be measured; a centrifugally-operated element pivoted on the shaft and revolving therewith; a sliding element mounted on the shaft for rotation therewith connected with said pivoted element; a pivotally mounted index finger and a graduated scale over which the index finger swings; a pivotally mounted cam carrier operatively connected with the index finger, and-a cam thereon whose cam edge or surface is acted'upon by pressure thereagainst of the sliding element for converting the sliding movement with modification into the swinging movement of the index finger.

7; In aspeedomet-er, a shaft adapted to be driven by the mechanism whose speed is to be measured; a centrifugally-operated ele ment pivotally mounted-on the shaft for rotation therewith and oscillation about its pivot toward andfrom the axis of the shaft; a circular disk mounted on the shaft for rotation therewith and sliding thereon and connected with the pivoted centrifugal'element for such sliding movement; a pivoted cam carrier having its cam edge or face acted upon by the periphery of the disk in the slidmg movement of the latter; a spring which resists the centrifugal movement of the pivoted element; an index finger connected with the cam carrier for swinging about its pivot in the swinging movement of the latter, and a graduated dial over which the index finger vibrates.

8. In a speedometer, a shaft adapted to be driven'by the mechanism whose speed is to be measured; a centrifugal element pivotally mounted on the shaft for rotation therewith and swinging about its pivot toward. and from the axis of the shaft; a disk mounted on the shaft for rotation therewith and sliding thereon and connected for such sliding movement with the pivoted centrifugal element; a cam carrier pivoted for swinging in a plane parallel to the axis of the shaft, the plane of rotation of the pivotal axis of the centrifugal element being intermediate the disk and the pivot of the cam carrier; a cam mounted on such carrier having its cam edge divided and located part at one side and part at the opposite side of the plane containing the axis of the shaft and parallel to the pivot of the cam carrier, the disk having a lateral peripheral flange which at opposite sides encounters successively the two divided portions of the camedge; an indicator oppositely connected with the cam carrier, and agraduated scale bver the indicator which is moved by such connection.

' 9. In a spee'dometer,-a,.shaft adapted to be driven by the mechanism whose-speed is to be measured; a centrifugally-operated element carried by the shaft; a spring which re sists the centrifugal movement; an element thereon whose cam edge or surface is acted IIC upon by pressure thereagainst of said long i- Chicago, Illinois, 13th day bf October, tudinally-moving element for converting the 1906. v latter, with modification, into the movement of the indicator, and a spring which resists JOHN STEWART 5 the movement of the cam carrier. 1 In the presence of In testimony whereof, I have hereunto set EDWARD T. WRAY my hand, in the presence of two Witnesses, at J; S. ABBOTT. 

